Thanks for the kind words! Spells shouldn't miss... unless you play Electro Calefaction, which has a 10% chance to miss (this is denoted in the tooltip which I unfortunately hid too well, you can find it by hovering over the spell name in the spell altar). The effects should stack, because I did not have time to implement it differently, though the applications are all tracked independently (if an enemy is blinded three times it should only have a 12.5% chance to hit) - if that wasn't the case then it's a bug. (Yes the Mocktopus is the final boss, good job for making it there :) )
It must have been Electro Calefaction (the one with double damage, if I remember). I think I used that way too often :) Now I understand the stacking mechanism. When I applied blind multiple times, they all showed up next to each other on the enemy, as two blind(1)'s not adding up as blind(2). And I expected the stacking mechanism to work like blind for two turns. My bad :) This makes perfect sense now. Thanks!